Blurring Labels in Sencha touch Chart 2.1 beta version

We have developed an application in sencha touch 2 and integrate Sencha touch charts for column chart.
It works well in chrome and safari browser as well in Android emulator .But in IOS device the labels are in charts seems blurring. We couldn't found the solution.
Test Case:
HELPFUL INFORMATIONScreenshot or Video: